Myocardial infarction ("heart attack") is one of the most common causes of morbidity and mortality in the world. The sudden cessation of coronary blood flow leads within hours to massive death of heart muscle cells by apoptosis and necrosis. Prompt myocardial reperfusion via angioplasty/stenting is currently the optimal treatment, but its effectiveness is limited by a narrow therapeutic time window. Work in lower organisms and mammals has demonstrated that a significant portion of cell death - both apoptosis and necrosis - occurs in a deliberate and highly regulated manner. This suggests that cell death during myocardial infarction can be therapeutically manipulated. Extensive work from the PI and others has delineated multiple mechanisms of cell death in the heart. Importantly, this work has shown that heart muscle cell death during myocardial infarction can be inhibited resulting in the reduction of infarct size and preservation of cardiac function. We wish to move these discoveries forward using a chemical biology approach through the following aims: Aim 1. To perform a high-throughput cell-based primary screen for small molecules that modulate the death of heart muscle cells in response to death stimuli relevant to myocardial infarction. Our preliminary studies, developed in conjunction with the Sanford-Burnham Institute, demonstrate the readiness of our assay. Aim 2. To further evaluate chemicals that influenced cell death in the high-throughput screen for broadness of effect against other death stimuli and cell types, and for pathway specificity. More stringent and specific cell death assays will be employed. In addition, targeted pathways will be mapped. Aim 3. To test final probe(s) and their best related analogs in an ex vivo model of myocardial infarction using intact, isolated, buffer-perfused hearts. To our knowledge, this is the first unbiased chemical screen directed at myocardial infarction. It is hoped that the probes generated will both (a) facilitate the future delineation of mechanistic linkages connecting apoptosis and necrosis, an issue of fundamental importance;and (b) provide the basis for the future development of drugs that reduce infarct size and retard its progression during myocardial infarction. PUBLIC HEALTH RELEVANCE: Myocardial infarction ("heart attack") is one of the most common causes of disability and death in the world. During myocardial infarction, large numbers of heart muscle cells die. This application proposes to identify chemicals that can be used (a) to determine how heart muscle cells die and (b) to create a medication that reduces this cell death.